A Crumb for the " Modern Symposium" 71 



imperceptible molecules of which perceptible bod- 

 ies are composed. The discovery of the " correla- 

 tion of forces " was the discovery of the fact that 

 any one of these kinds of molecular motion is con- 

 stantly liable to be transformed into any one of 

 the other kinds, or, now and then, into the molar 

 motion of a perceptible body. Heat is all the 

 time being converted into light, or into electric- 

 ity, or into the peculiar kind of undulatory mo- 

 tion known as " nerve-force " and vice versa. 

 And the law of the correlation is that, when any 

 one of these species of motion appears, an equiva- 

 lent amount of some other species disappears in 

 producing it. Throughout the world the sum-to- 

 tal of motion is ever the same, but its distribution 

 into heat-waves, light-waves, nerve-waves, etc., 

 varies from moment to moment. 



Let us now apply these principles to the case of 

 an organism such as the human body. All of the 

 " force " i. e., capacity of motion present at 

 any moment in the human body is derived from the 

 food that we eat and the air that we breathe. As 

 food is turned into oxygenated blood and assimi- 

 lated with the various tissues of the body which 

 themselves represent previously-assimilated food 

 the molecular movements of the food-material 

 become variously combined into molecular move- 



